peculiar afFection of the shoulder joint, pgrticularly when the history of the case is known, cannot well be con founded with any other disease of the articu. lation with which we are acquainted. Scro fulous caries of the bones of the shoulder joint May have some symptoms in common with the chronic disease we are describing, but there is more pain and more wasting of the Muscles of the arm and fore-arm, and more sympathetic disturbance of the constitu tion in the case of articular caries of the shoulder than in that of chronic rheumatic arthritis of this articulation ; and while the former case usually proceeds to suppuration, or to anchylosis of the joint, these processes never take place in the latter.
In the chronic rheumatic disease, the op posite shoulder joint will, in general, be found symmetrically affected ; a circumstance we have never yet known to have been the case in a chronic arthritis, or articular caries, of the shoulder.
The history of the case of chronic rheuma tic arthritis usually betrays its nature by the general rheumatic pains the patient reports himself to have suffered froin ; by the disease not being confined to the one articulation ; by the enlargement of the bony prominences about the joint, although the muscles are wasted. In both cases there may be crepi tus felt on moving the joint and on making pressure ; but the efforts to elicit crepitus, and the pressing together of the articular sur faces cause, in the case of chronic arthritis, or articular caries, so much pain, that the patient shrinks back from our attempts at rnaking these trials ; while in the ordinary case of chronic rheumatic arthritis of the shoulder, when even it appears as a local disease confined to one or two articulations, we find we can even rudely press the head of the humerus against the surface of the glenoid cavity without causing the patient pain, just as we can, in the case of the same disease when it affects the hip joint, press the head of the femur against the acetabulum without causing the least uneasiness to the patient (see Vol. II. p. 799.).
No doubt some few cases of chronic rheu matic arthritis of the shoulder joint in the living and in the dead have been mistaken for partial dislocation of the head of the humerus, the result of accident ; but we are of opinion that, as the chronic rheumatic affection is daily becoming better known to the profes sion than formerly, such errors will no longer be committed, particularly when the anato mical characters of this disease have been more fully studied by the profession.
Anatonzical characters. — When we ana tomically examine the shoulder joint of a patient who has long laboured under this chronic disease in the articulation, we notice on removing the integuments that the deltoid muscle is unusually pale, and that the inter stices between its fibres are occupied by an unhealthy-looking fat. This and the sub jacent capsular muscles are in a state of atrophy. The capsular ligament is generally altered in form and structure, and it will be sometimes found to have abnormal attach ments above to the acromion or coracoid process ; and, below, its attachment to the anatomical neck of the humerus is some times partially interrupted, allowing of an interval which in some forms of the disease permits the head of the humerus to pass through it.
The capsular ligament is occasionally in creased in thickness, and its fibres are hyper trophied ; and it is generally :more capacious than natural, showing that effusion of synovia to a considerable amount had existed, although the external signs of this phenomenon are not usually evident. When the interior of the synovial sac is examined, it will be found to present evidences of having been the seat of chronic inflammation. Bunches of long or ganised fringes hang into the interior of the synovial sac; and many of these vascular fimbrix, which in the recent state are of an extremely' red colour, surround the corona of the head of the humerus. We also notice rounded cartilaginous productions, appended by means of membranous threads attached to the interior of the various structures which compose the joint. Some of these foreign bodies are small, others large. Some are round ; hut their shapes are various. Besides these rounded cartilaginous bodies, we occa sionally find osseous productions of a mill tangular form added to the edges of the gle noid cavity, deepening it, and increasing the articular surface for the reception of the head of the humerus, which usually is in such cases much enlarged.
The intra-articular part of the long tendon of the biceps is very seldom to be seen in the interior of the joint ; but immediately out side of the capsular ligament the latter tendon will generally be found to have contracted a firm adhesion to the superior extremity of the bicipital groove (fig. 428. a.).